


Transformations

by Gilli_ann



Category: Merlin (TV)
Genre: Action/Adventure, Alternate Universe - Canon Divergence, Angst with a Happy Ending, BAMFs, Canon Era, Drama & Romance, Family Secrets, Hurt/Comfort, M/M, Magic, Magic Revealed, Mythical Beings & Creatures, Sea Monsters, Transformation, Whump
Language: English
Status: Completed
Published: 2018-12-28
Updated: 2018-12-28
Packaged: 2019-09-07 11:19:02
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,864
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16853038
Author URL: https://archiveofourown.org/users/Gilli_ann/pseuds/Gilli_ann
Summary: A sea-monster threatens Camelot, demanding a Pendragon as sacrifice before it will stop its reign of terror. Arthur is ready to give his life for his people, but Merlin and Morgana keep intervening, causing complications and dramatic developments that ultimately may usher in a golden age filled with love and magic.This story takes place (and goes AU) immediately after 'Merlin' season 1.





	Transformations

**Author's Note:**

  * For [LFB72](https://archiveofourown.org/users/LFB72/gifts).



> Dear LFB72, the happiest of holidays to you! :)  
> This fic has been written based on a mix of several of your excellent prompts, and I've also tried my best to include a sprinkling of your suggested tags. I had a lot of fun writing this, and I hope you enjoy the result.
> 
>  **Thank you:** My encouraging and ever efficient beta, G, deserves a lot of thanks. And a big thank you to the MH mods for organizing the fest once more! The holidays wouldn't be the same without it.
> 
>  **Disclaimer:** The BBC's Merlin belongs to the BBC and Shine TV. I intend no copyright infringement and make no profit from writing this.

  


The monster's eyes glowed red, and so did its huge maw, a hint of fire contained behind rows of jagged teeth. The massive creature had a serpentine body, heavily muscled, coil upon black coil breaking the waves as it rose from the Northern sea.

Striking with lightning force, it snatched one of the village girls on the nearby beach, and swallowed her in one gulp. She was dead and gone, even as her dropped basket still rolled across the sand, spilling the mussels she had gathered for her family's meal.

The other girls stood as if frozen, too frightened to run or scream. The monster towered above them for a moment, lashing the salt water with its tail. It spoke with a roar. "My hunger will not be satisfied until I have been given a royal Pendragon of Camelot to devour. Tell the king this!" 

In the next instant, it was gone, leaving behind an unruly sea and white-crested waves crashing to shore.

The villagers knew without a doubt that this had to have been a creature of dark magic, a monster of the underworld. Such a fearsome being would never belong to the natural world, and no ordinary creature would be able to speak in the human tongue. 

They mourned the loss of their daughter, sister, and friend, but Camelot seemed very far away, and no-one wanted to risk the journey. 

Then, just a few days later, the monster struck again, just a few miles further south. The victims were two small girls playing by the sea, their mothers doing laundry nearby. The two women dropped everything and ran screaming to the shore, but it was too late. The monster roared its message at them and disappeared into the depths of the sea, taking the children away forever. 

The creature of darkness struck again and again, each time a little further south and closer to Camelot, and each time leaving exactly the same message.

The frightening tale of the sea-monster robbing so many coastal towns and villages of their girls and young women travelled far and wide. Several villagers, frightened that their daughters would be the next victims, set out for Camelot, intending to plead with the king for help against the menace. By then, the tale had already reached Camelot along the trade routes, and the danger and devastation had only grown in the telling.

And the Lady Morgana kept having nightmares about the monster nearly every night.

*****

"I have sent ten of my best knights north," Arthur said, raising his arms to let Merlin fasten his sword belt. "I do not doubt that there is some sort of monster, but I need facts, not these horror stories and wild imaginings born of superstition and fear."

Merlin took one step back, looking Arthur over to check that everything was as it should be with the armour. He reached for the sword, handing it to Arthur without a word.

"Come on, Merlin. Out with it," Arthur said, accepting the blade and sheathing it with practiced ease. "Your silence speaks so loud that I shall have to cover my ears."

"What if the tales are true? What if Morgana's nightmares are somehow prophetic?"

"Don't let your imagination run off with you completely," Arthur said. "You're such a girl's blouse sometimes. We have fought monsters before. Remember that Afanc? Or the Questing beast? Those were magical creatures, intent on harming Camelot, yet now they're dead and gone, and we're still here."

Merlin bit his lip, lowering his eyes. Yes, the Questing beast was dead, and Arthur was alive and well, but only because Merlin had bargained another's life away. He had thought he was giving up his own life to save Arthur's. Nimueh had failed to tell him that the life about to end would not be his, but King Uther's. 

Arthur had become king while still gravely ill. He missed his father immensely, and blamed dark magic for King Uther's sudden death— a man in his prime, struck down by a bolt of lightning on a sunny day? It had to be vengeful sorcery at work. Because of the suspicious circumstances of his father's death, Arthur continued to fear and distrust sorcery. He had no intention of lifting the ban on magic, and the punishment for practising sorcery was as severe as ever. 

There was nothing else Merlin could do than continue to hide his powers in plain sight. He felt guilt and compassion at Arthur's overwhelming grief, even if he truly hadn't had a choice at the time. 

Nimueh was still out there somewhere. If Merlin ever met her again, he intended to ask her whether she'd known that King Uther would be the one to pay with his life to save Arthur's. There was a certain poetic justice to it, but Nimueh's schemes were convoluted, and her reasons were always her own.

He briefly wondered whether she was behind the fearsome sea-monster that now menaced Camelot and Arthur. Somehow, he didn't think so. Surely Nimueh would be content now that her arch-enemy Uther was dead?

"Oh, stop looking so doleful, Merlin," Arthur said, the irritation in his voice bringing Merlin back to the present with a jolt. "My knights will soon be back with proper information, and then we'll be able to make a plan. I don't intend to rush to the seaside and stand around offering myself up as a sacrifice just yet."

"I know, Sire. I'm sorry."

"Merlin, being respectful? And apologizing? Now I've heard it all. Judgment day may be closer than I thought," Arthur laughed. He grinned at Merlin and left to oversee the training of new recruits, one of his favourite activities. It always put him in a good mood.

Merlin remained in the royal chambers, half-heartedly making the bed and tidying the rooms, once more preoccupied with worries for Arthur's safety.

*****

The knights did not return from the north. Only Sir Leon, the youngest one among them, very newly made a knight, came back from their quest.

Although he had travelled for days since the group of Camelot's best knights encountered the monster, Leon still looked deeply shaken as he made his report to Arthur and his council.

"We kept to the coastline. Sir Dinadan thought we would surely have news of the creature, or even see it ourselves. He was more right than he knew." Leon shook his curly head. "We were riding along the beach near the Fort of Firiel, when the monster suddenly appeared. We had no warning. I have never seen anything so monstrous, nor so frightening. It had the shape of a gigantic black snake with fins, but with a dragon's head. The noises it made were louder than thunder. Our horses went wild and threw us. We couldn't control them. And then the monster— Sire, it used its tail and swept all the knights but me into the sea. It pulled them under. They drowned."

"Sir Aglovale, good Cador, and Geraint— they're all gone?" 

"Yes, Sire." Leon bowed his head in sorrow. "I am sorry to bring you such sad tidings. I will never know why the monster chose me to survive and to deliver its dire message."

Silence reigned for a while in the council-chamber. Eventually, Arthur cleared his throat and asked; "What message did the monster give you to deliver, then?"

"It ordered me to tell my king that it required the sacrifice of a royal Pendragon at the Cliffs of Aval. Until then, it would continue gorging on the women of Camelot." Sir Leon shuddered. "I will never forget that roaring, inhuman voice, Sire."

"You did all that you could, and you've served me well in bringing us this news quickly," Arthur stated, his voice calm, but his face pale. "I will not forget that, Sir Leon. Now you must leave us. Go eat and rest. I may have need for your courage and that of your fellow knights soon enough."

*****

It was late. Arthur had dismissed his councillors and knights for the night, but had asked Gaius to stay.

Merlin hovered behind the king's chair, trying to hide how jittery he was. He didn't like Arthur's wearily determined look.

Arthur drew a hand across his forehead, as if to clear his mind of unwelcome thoughts. "Well, Gaius, you've heard what Leon had to say. There is no-one at court with better knowledge of magical creatures and malevolent sorcery than you. I need your advice. What do you think—"

The door to the chamber suddenly swung open, hitting the wall with a loud bang. The three men in the room startled, Arthur's hand instinctively going to the hilt of the sword he wasn't currently wearing. 

"Arthur Pendragon! You miserable lout, did you intend to keep me in the dark about Leon's report?" 

Morgana's green eyes were blazing, her purple gown streaming behind her as she strode into the room. Gwen followed behind her, ducking her head and looking worried, apologetic at intruding on the king, but unable to do differently.

"Mor-gana," Arthur replied, in that special tone of voice he reserved for his quarrels with King Uther's beautiful ward. "Please come in. Do make yourself at home. There is nothing you can contribute here, so I saw no need to involve you."

"Do you intend to sacrifice yourself on the sly and leave me to find out about it afterwards? What a coward you are!"

Arthur didn't take the bait, but neither did he deny her heated accusation. "I am the last royal Pendragon in Camelot, and I have a responsibility to my people. Should I let a monster devour every girl and woman in Camelot while I stay at home in comfort and safety?"

Morgana sat down, the violent anger draining out of her. She was very pale, and there were dark circles under her eyes.

"Of course not," she said. "But there has to be another way. My nightmares...." Her voice trailed off, her eyes seeking Gaius. Gwen patted her hand, and sat down next to her. Merlin sent them a small encouraging smile.

"I was about to ask Gaius his advice when you barged in like a wailing banshee." Arthur turned back to Gaius. "To your knowledge, is there any means of killing this thing, or rendering it harmless? What sort of power is fuelling this monster, and how can we stop it?"

"Sire, there is no doubt that it is a creature of dark and ancient magic. Where it came from, I cannot say. The strength of this sorcery seems far beyond anything the High Priestesses of the old religion were able to command. But as you know, all the powers of magic opposed your father, and you are maintaining his laws."

Arthur shrugged, annoyed. "Yes, there's been some sort of sorcerous attack or magical monster nearly every week this last year. But we have always managed to defeat them. Why should this be different?"

"From the descriptions, I believe we may be dealing with a being of immense powers, only known in the most ancient legends. It is described there as a powerful whale or monstrous serpentine creature, whose name is Cetus. It is a magical creature dating back to prehistory, like the fire-dragons of old."

"How do we kill it?"

"Sire, on that score the legends are silent. It is said that many tried, but none succeeded. In the past, Cetus always continued its rampage until its demands had been met."

Silence fell in the council chamber. They all needed a moment to digest Gaius's words.

"How do you know that it's Arthur this Cetus monster wants?" Morgana suddenly asked, taking the discussion in an unexpected direction.

"Do you know any other royal Pendragons hereabouts?" Arthur huffed. 

Gaius looked up, startled. His eyebrow twitched. But he didn't speak. 

"I only mean— the monster is only devouring women and girls. You'd think it would want a woman as its preferred sacrifice. Other monsters and dragons of legend always wanted a princess as tribute, didn't they?"

Arthur shrugged. "It seems that in this case, since there is no Pendragon princess, Cetus is willing to settle for the next best thing."

"I have had nightmares about this monster. I know what it looks like. Nearly every night I see it, with waves crashing all around its body. It seems to be facing me. Arthur, I was Uther's ward. Could it be that it is me Cetus wants?"

"Nightmares!" Arthur scoffed. "Morgana, I know that they trouble you greatly, but they are just dreams, fears preying on your mind when you are the most defenceless."

Once more, Gaius moved on his seat, but didn't speak. Merlin looked from one to the other. All of them were tired and agitated. Gwen seemed on the verge of tears. Morgana looked angry.

"Just dreams? So you keep telling me, Arthur. Gaius, too. But I have had previous nightmares that proved true. I saw the Questing beast before it attacked you. I think—" Morgana squared her shoulders, raising her chin defiantly. "I think my dreams are visions of the future. I think I'm a seer."

"Morgana, that would make you a sorceress," Arthur said dismissively. "I don't believe it. Don't waste our time like this. We have more pressing matters to discuss."

"Waste your time?" Morgana rose to her feet, tense as a bowstring, her face livid. "These visions that come close to killing me, these glimpses into a frightening future, you think they waste your precious time?" 

To Merlin's horror, he saw Morgana's eyes changing colour. Suddenly, as she fixed Arthur with her enraged glare, they glowed golden like the sun. 

Merlin reacted on pure instinct. He threw himself forward, pushing Arthur to the floor. 

A bolt of bright light shot across the room, passing right through the space where Arthur was sitting only a moment earlier. The blast hit a wine carafe on a side-table, the crystal disintegrating in a puff of shimmering dust. Crimson liquid splashed across the table and started dripping to the floor. It looked like blood.

For a moment, everyone in the room remained frozen. 

Morgana clapped a hand to her mouth. Her eyes, green once more, went wide with shock and horror. "Oh no, no, I didn't mean to, I don't know what—"

"My lady! Morgana!" Gwen jumped to her feet, gripping Morgana's arm. She looked shaken, but did not back away from her mistress.

Arthur pushed Merlin aside, and sat up. "That was sorcery," he said evenly. "You really do have magic."

"I... I..."

"Arthur," Merlin pleaded. "Don't do anything rash. We have a monster to worry about. This will have to wait."

Arthur got to his feet. His shoulders slumped. "Who will I now leave the rule of Camelot to, if...."

Morgana had dropped down on her chair as if her legs had lost all their strength. She hid her face in her hands. Gwen anxiously patted her back. 

Gaius cleared his throat. He looked back and forth between Morgana and Arthur. Merlin felt a chill in his heart. That look on Gaius's face— he knew it well enough. Whatever his old mentor was about to say, it wouldn't be pleasant. They were about to get bad news. 

"Sire. Lady Morgana. There is a secret that King Uther made me swear not to tell a living soul as long as I lived. I intended to take it to my grave. But under the current circumstances, I think it is my duty to break my solemn vow. There is something that you both need to know."

He fell silent for a moment. All eyes in the room were upon him.

"Twelve years ago, when you were close to death with fever, Morgana, King Uther told me to save you at any cost. He told me that he loved you as a daughter, - because you actually _were_ his daughter."

Merlin had thought it would be impossible for Morgana to turn any paler. He'd been wrong. 

Arthur took a step forward, staring at Gaius as if the old physician had grown two heads. 

"That's impossible." Morgana's voice trembled with emotion. "My father— Duke Gorlois is my father. There is no doubt about that."

"I'm sorry, my lady. I do not mean to cause you distress, but I'm speaking the truth. Uther told me that your mother - the Lady Vivien - had grown lonely while Duke Gorlois was on campaign, and...." Gaius grimaced, leaving his listeners to imagine the rest. 

"I don't believe this, Gaius," Arthur said coldly. "I would be happy to think of Morgana as my sister, but you're telling me that father cheated on my mother, the love of his life, because a lady at court was lonely? That's ludicrous!"

"Uther was a very complicated man," Gaius replied. "There is no doubt that he loved Queen Ygraine above everything. There is also no doubt in my mind that he was telling the truth. Morgana is his daughter. She is your half-sister, Sire."

Arthur sat back down with a thump. He shook his head tiredly. "I can't think about this right now. We have to focus on the monster menacing Camelot."

Gaius gave the young king one of those mildly annoyed looks that Merlin knew all too well. "That's exactly what I'm doing. I think Morgana was right when she said that the monster requires a female sacrifice. _A royal Pendragon of Camelot_ , wasn't that its demand?"

Morgana laughed, a brittle and broken sound. Her eyes stood full of tears. "I have magic. I'm a Pendragon. I will have to die soon and be torn apart by a monster. Is there anything else I need to learn before this night is out?"

Arthur rounded the table, sitting down next to her and hugging her tight. "This has been far too much for one night. We are overwrought and exhausted, all of us. If we get some sleep, we'll see things more clearly in the morning."

"I'll still be a sorceress tomorrow."

"You'll hardly burn down Camelot on a sudden whim within the next few hours, Morgana. We'll talk no more about this tonight. Get some sleep," Arthur repeated stoically. "Gwen, would you stay with Lady Morgana tonight?"

"Of course," Gwen replied. She had been sitting still as a statue, making herself small, and seemed relieved to find something practical to do. "Please come with me, my lady."

"Merlin, Gaius, thank you for your service today. Merlin, I shall expect to see you with my breakfast in the morning," Arthur said. "Good night."

His dismissive tone brooked no argument. Silently, all four of them left the king to himself, Morgana and Gwen turning towards Morgana's chambers, Merlin and Gaius returning to the Court physician's rooms. 

"Is it true about Morgana? Is she really Uther's daughter?" Merlin asked Gaius as they walked.

"Are you accusing me of lying, dear boy?"

"No, but— I wasn't expecting that."

"Were you expecting her to be a sorceress, then?"

"Yes. And so were you."

Gaius didn't try to deny it. "I've had my suspicions. Her dreams have sometimes seemed prophetic. But with a father like Uther, it was better for her if she never learned the truth about her powers."

"So she truly is a Pendragon?"

"She is indeed."

Harsh realization dawned on Merlin. "You want her to be sacrificed instead of Arthur. You want the monster to rather take Morgana!"

"Arthur will become a great king, and bring a golden age of peace and prosperity to all of Albion. Wasn't that what the great dragon told you many times before you set him free to fly off?" Gaius stopped, turned towards Merlin, and looked him in the eye, a piercing glare. "If only one of our two Pendragons can survive, then yes, I want that one to be Arthur. You would make the same choice, Merlin, don't pretend otherwise."

"I want to find another way. I want the monster vanquished."

"We cannot always get what we want. Life is sometimes unfair, and difficult choices must be made."

They walked the rest of the way in silence.

*****

Merlin couldn't manage to fall asleep until the break of dawn. Twisting and turning on his cot, he tried to find a way out. If only he hadn't set the great dragon free after Uther's death. Kilgharrah surely could have provided him with a spell or a new magical weapon to defeat this Cetus, but he was gone. Merlin knew of no way to make him return.

As a consequence of his troubled night, he overslept. When he stumbled down the steps from his bedroom, he found Arthur standing in the bright light of day in Gaius's main room, rifling through the bottles and vials on the medicine shelves. 

"Arthur?" Merlin said, confused, still half asleep. "Why are you here? Where is Gaius?"

Arthur turned towards him with his most arrogant and annoyed expression. "Gaius is doing his physician's round in the lower town. While you, who must possibly be the worst servant any king ever had the misfortune to be afflicted with, have been sleeping half the day away. I have had no breakfast."

Merlin ducked his head, drawing a hand through his hair, embarrassed. "Uhm, oh... eh." He really had no excuse this time. 

Arthur put one hand in his pocket, depositing some object there, and turned to leave. "Shut up, you utter buffoon, and follow me."

Marching through the door without a backwards glance, Arthur left Merlin to pull on his boots, grab his jacket and run after him as fast as he could. 

"I had word from the village of Celliwig early this morning. Cetus was seen there yesterday, and grabbed a goatherder girl from the cliffs. Celliwig is barely two hours' ride from here. We're out of time," Arthur said, without turning around. "Today is the day."

Merlin nearly stumbled in his efforts to catch up. "What will you do?" he asked, his mind reeling from the unwelcome news.

Arthur stopped so abruptly that Merlin crashed into his back. The king turned around, wagged a finger in Merlin's face, skewered him with his fiercest royal glare, and said; "I'll tell you what _you_ will do. You will go to the kitchens and fetch a proper lunch for two. I must have a talk with Morgana, and I think she and I should have a meal together. It eases tension."

Merlin bowed, and backed away. Arthur's mood made him uneasy. "At once, Sire. I'll bring you the tastiest fare that cook can provide."

"And bring us a bottle of the best wine, too!" Arthur called after Merlin as he scampered off. "We'll certainly need it!"

*****

When Merlin arrived at Arthur's chambers, carrying a tray heavily laden with food and wine, Morgana was sitting by the table. She looked as pale as a ghost, but quiet and composed. The bright midday sun streaming through the stained-glass windows cast reflections of shimmering red and blue across the floor and the table.

Merlin hurriedly set out the tableware and put the food on the table, placing a small bowl of fruit in front of Morgana. Neither of the Pendragons said a word while Merlin laid out the meal, but eventually Arthur spoke. "Give me the wine bottle to open, Merlin. You're so clumsy, you'll likely spill half of it." 

Bottle in hand, Arthur went to a side-table where two silver goblets had been placed. His back to the main table, he carefully poured the crimson liquid into each goblet, walking over to place one in front of Morgana. 

"To your very good health, sister."

Morgana looked up, startled, but raised the goblet to return Arthur's toast, sipping the wine. "To your health, Arthur. My brother as well as my king, now. How strange."

"Delicious wine, don't you think? Let's eat."

"I don't think I can," Morgana said. "I am not well."

Merlin took up position in the shadows of Arthur's big cabinet, trying to make himself invisible, hoping he'd not be dismissed. He needed to hear this.

"Morgana, I have been thinking— I want to assure you that I don't hold your sorcery against you. It is obvious to me that you can't control it, and don't know how to use it deliberately, neither for evil nor for good."

"The magic has chosen me, not the other way around, Arthur. It frightens me," Morgana whispered.

"Perhaps Gaius can help you learn to control it, or suppress it? I want to see you strong and confident again."

"That's reassuring, Arthur, but it hardly matters much, does it? When Cetus comes, I will have to sacrifice myself to save our people. That much is obvious, and I am ready." Morgana sighed. "In a way, it will be a relief. No more doubts, no more fears. And my magic will die with me."

"It will take many days yet before Cetus arrives," Arthur said, his voice light. "We have enough time to come to terms with all of this and to look for a better solution."

Merlin blinked, shaking his head in surprise. Arthur frowned at him forbiddingly. Merlin stayed silent.

Morgana lifted her wine goblet, drinking long and deep. "It's good of you to be so optimistic, Arthur."

"I don't want to have gained a sister only to lose her again," Arthur said simply. "You are brave and true, and your heart has always been in the right place. Camelot needs you."

They turned their attention to the food for a moment, Morgana picking listlessly at a small bunch of grapes. She yawned.

"I really do not feel well, Arthur. I'm so tired." Morgana got to her feet, looking unsteady, supporting herself on the table. "Dizzy. I'm dizzy. The room is spinning—" 

Merlin saw only the whites in her eyes. She crumpled to the floor, unconscious.

"Morgana!" Merlin rushed to her side, supporting her head, looking up at Arthur. "Aren't you going to help her? I must fetch Gaius!"

"There's no need for that," Arthur said evenly, finally rising from his seat. "She's had one of Gaius's most potent sleeping draughts, I laced her wine with it myself. She'll be none the worse for it when she wakes up tomorrow as the new queen of Camelot.

*****

The king's horse was skittish, perhaps sensing the tense mood. Arthur patted its neck, stroking the brown coat, murmuring a few calming words.

Drawing a deep breath, he adjusted his red cloak before turning to Merlin. "No, I do not want you to follow me. Stay here, Merlin. That's an order." 

Merlin opened his mouth to object, but Arthur lifted a hand, silencing him. "Once she awakens, Morgana will need your service and your friendship, just as you've always been my true friend. Although I have to say in all honesty, you're no more than a barely passable servant."

Merlin stifled an unwelcome sob. "If you weren't such a royally arrogant prat, maybe I would have been more obedient," he countered, but the joke fell flat.

They looked each other in the eye, sharing unspoken emotions, and simultaneously reached out to clasp hands. 

"I understand that you want to spare Morgana. I only wish that I could take _your_ place," Merlin said.

"I know," Arthur smiled fondly, his eyes warm. "I know you would do it, too. Despite what I keep telling you, you're a brave man, Merlin. Morgana will need you by her side. Since this has to be, I couldn't wish for a better fate than making my sacrifice, knowing that I'm saving my people, and that Camelot will be left in capable hands."

Merlin struggled to keep his composure. 

"Goodbye, Merlin," Arthur said, his voice even, and his face calm. His blue eyes shimmered. "Thank you."

Mounting his horse with ease, Arthur looked at Merlin's face one last time, nodded, and pulled at the reins. He galloped across the courtyard, the horse hooves clattering loudly on the cobblestones. All too soon, horse and rider were gone from view. 

Merlin remained motionless for a moment, his eyes blurry as he looked across the yard. Though knights and burghers were milling about on their everyday business, the large space seemed empty and forsaken. Without Arthur, Camelot was a void. Was there ever a more noble and honourable king, so ready to give his life for his people? Was there ever a man more worthy of Merlin's love?

Merlin wondered whether Arthur truly believed that he would obey him this time, and remain in Camelot while Arthur faced certain death. They had already come up against many perils together, and Merlin had always willingly followed Arthur into danger, staying as close to the king as his own shadow.

But this time he couldn't follow Arthur at once, however much he wanted to. There had been no time for Merlin to make any arrangements, and now there was something he desperately needed to do. He had to get hold of the only sword that had been made to kill both the living and the dead, the sword that had been forged in the dragon's fire to vanquish even the most powerful magical foe. 

He had to collect Excalibur from Lake Avalon, where he himself had hidden it away, and bring it to Arthur. 

Time was short. Merlin turned and ran for the stables.

*****

When Merlin arrived at the Cliffs of Aval, the sun hung low in the western sky, making each wave and ripple on the ocean sparkle with reflected light.

He was weary and anxious. He'd had to exert his magic much more than he'd liked to in order to make the devious Sidhe return Excalibur to him from the lake. Now his powers felt uncomfortably depleted, just when he might need them the most. He leaped from his tired horse's back and ran towards the far steep cliffs facing the western sea, jumping from rock to rock, hampered by the weight of Excalibur in his hand. 

The brilliance of the sun and the shimmering waves nearly blinded him. He scanned the cliffs for any trace of Arthur. Had the monster already seized its prize? Was Arthur gone? 

Frantically hoping that he hadn't come too late, Merlin paused, breathing fast, his heart racing. 

And there— there he was, standing calmly on a rock protruding above the water, facing the sinking sun. Arthur looked like a vision of glory in his crimson cloak, tall and handsome, his hair like a golden halo. 

Merlin gasped in relief. He'd made it in time!

"Arthur! Arthur, it's me! I've brought you a sword made to fight magic monsters," he called, hurrying forwards. 

Arthur turned to look at him. His serene expression turned into a frown of worry and displeasure. "What are you doing here? Didn't I order you to stay at home?"

"Did you ever know me to obey orders like that? You're not half bad as royal prats go. I don't want to lose you."

Merlin had finally reached the massive rock where Arthur stood. One final jump, and he was right next to Arthur. He could feel the dizzying pull of the sheer drop beneath them, could hear the moaning and mournful noise of the waves, endlessly moving, slowly grinding the cliffs to dust. Merlin felt wobbly on his feet from relief and exhaustion.

"I've brought you Excalibur, your sword," he repeated, balancing the dragon-burnished blade on his two palms and presenting it to Arthur.

"It's not mine, I've never seen it before," Arthur grumbled. "And anyway, no sword will help in a battle against Cetus. That much has been made clear to us."

"This sword will make a difference," Merlin insisted.

"Merlin, leave me! Leave at once! Cetus may appear at any moment. I want you away from here. I couldn't bear it if you—"

There was a booming, groaning noise as if the seas were parting to release all the darkest powers of the underworld. Huge waves crashed against the cliffs below them. Cetus rose from the waves, the massive serpent-like body seemingly reaching for the sky, the immense head with its red maw and fiery eyes towering above the two of them.

Both Arthur and Merlin took an involuntary step backwards. The sheer hulking presence of the monster was incredible, blocking out the light from the sinking sun. Fin-like structures along the powerful body flared to either side and made its bulk seem even more immense. 

The booming voice that rang from Cetus's maw resembled the thunder of a rock-fall. "I seek a royal Pendragon."

Arthur stepped forward, righted himself proudly, met the monster's baleful glare, and responded; "I am King Arthur Pendragon of Camelot."

"Are you offering yourself as sacrifice?"

"I am. Though I would first like to know why you seek such a sacrifice," Arthur responded. 

"King Uther killed every dragon but one. The dragons were my closest kin of old. I demand retribution. I want revenge," Cetus growled, the sulphuric blast of its exhaled breath nearly making Merlin choke. 

"Very well. Once you have me, will you promise to harm my people no more, and to stay away from Camelot from this day forward?" Arthur asked with impressive composure. 

"You have my word."

Arthur glanced to the side, giving Merlin a push. "Let me make it clear that Merlin here, my stupidly loyal servant, is one of my people and therefore should not be harmed."

"It's you that I want, and now that I have you, I'll exact my vengeance," the monster roared, its head pulling back and its coiled body tensing as it prepared for the lethal strike. 

"Arthur!" Merlin yelled. "Use the sword. Now is the time. Save yourself and save Camelot!" 

It was too late. The monster struck like a monstrous viper, its jaws opening wide to seize and devour its willing victim.

Merlin threw himself at Arthur, pushing him out of the way so forcefully that Arthur nearly rolled off the rock ledge into the sea. 

There was only one way to save them now, and Merlin had no time to consider. He reacted on pure primeval instinct. 

As Cetus turned towards him in fury, bellowing like a hurricane, venomous fire blasting from its open maw, Merlin raised both hands towards the monster and screamed words of command, more powerful than he would have believed himself capable of. He was desperate. He knew that his eyes were blazing from the magic he felt himself channeling.

The beast halted in mid-air, its eyes bulging and its long body convulsing. Deafening roars rang across the sea, and Cetus's long tail lashed the cliffs so that huge boulders and pieces of the rockface careened into the water. Sea-spray and raging waves reached the rock that Merlin was standing on, making it slippery. 

Off to the side, Arthur held on for his life, fighting gravity that would pull him to his death, clawing himself back onto safer ground. He stared at Merlin in complete shock. 

Merlin sensed it almost immediately; the monster was too strong. He couldn't kill it, only hold it at bay for a while. Frantically, while maintaining the spell that kept Cetus from reaching himself or Arthur, he sought another solution. 

"Âgieldan êower eafoð âdôn me! _Yield your power up to me_ ," he chanted, reaching out to the monster with every part of his magic, feeling how that magic attached itself to Cetus's powers and pulled them back to Merlin. He was subsuming the monster's might into himself. Cetus had come to devour Arthur. Now Merlin was devouring Cetus instead. 

He felt himself shaking with the immensity of the power coursing through him, felt himself radiating magic so strongly that he risked disintegrating into pure light. He kept up the chanting, pulling more and more of Cetus's might into himself, consuming it, and becoming one with it. The monster was fighting him, rolling back and forth, using its whole mighty body to hammer the cliffs, roaring like thunder. But it couldn't break free, and its powers were waning. 

"Âgieldan êower eafoð âdôn me!" Merlin chanted, knowing that he had reached the limit of what his magic could do, what he himself could take and still survive. He'd have to sever the connection, but he struggled to do so. His powers and those of Cetus were too intertwined. He couldn't break free! He screamed in agony.

"Merlin!" Arthur called from the side, crawling towards him across the slippery rock. "Merlin!" 

"Arthur, take the sword. The sword! Help me. Kill the monster, or I'll die!"

Arthur staggered to his feet, bedraggled and stunned, Excalibur in his right hand. He raised the sword into the air. The monster convulsed, thrashing from side to side, its head and neck for one moment next to their rock. 

Arthur swung his sword. 

Had Cetus retained its full powers, no mortal weapon could have harmed it, and even Excalibur might not have been up to the task. But the monster was almost powerless now. Excalibur cleaved through scales and sinews, muscle and bone. With one mighty blow, Arthur beheaded Cetus. The venomous head crashed into the sea, while the monstrous body coiled and lashed out in one last frothing fury before sinking slowly beneath the waves.

Merlin fell on his face. He was so exhausted, he couldn't move a finger. He was hovering on the edge of unconsciousness.

Letting go of the sword, Arthur dropped to his knees beside Merlin, carefully rolling him over and pulling him into his arms. Merlin's head lolled back on Arthur's shoulder, his eyes closed. 

"Merlin, Merlin, Merlin. Can you hear me?"

It required too much effort to form words and speak them aloud. Merlin blinked once and lay as before, his breathing laboured but audible.

Arthur continued to cradle him in his arms, rocking him gently. He started to hum, a soothing, comforting sound.

Dusk was yielding way to night. It was cold and uncomfortable on the rocky ledge, buffeted by winds and occasionally drenched in salt sea spray. Arthur never budged, but did his best to protect Merlin from the elements.

"Don't you dare leave like this," Arthur eventually said, placing a cold hand on Merlin's forehead. "Come back now. I know you can do it. Come back."

Merlin blinked again, the barest hint of a smile touching his lips in the gloom. Reassured, Arthur held him close, occasionally murmuring encouragements, waiting patiently.

At long last, Merlin felt strong enough to sit up. He was shivering. "We should leave this place, find somewhere to rest," he whispered. 

Clouds had rolled in, and there was no moon. Even though the sea below cast a faint sheen, it was too dark for them to truly see each other. 

Arthur rose to his feet, and fastened Excalibur to his belt. Lifting Merlin, Arthur arranged him across his shoulder. It was not the first time that he carried a wounded man out of harm's way.

Getting back to firm land across the rocks and chasms in the darkness was a daunting prospect. Having considered for a moment, Arthur said; "Would it be possible for you to provide us with some light?"

Something unpleasant was roiling and pushing inside Merlin. Having consumed nearly all of Cetus's power, he should have been ready to take on the world, but instead he felt nauseous, weak, and drained. Nevertheless, he managed to cast a spell summoning a weak light, pooling around Arthur's feet. It was all he could manage.

"Thank you," Arthur said after a moment. "This will do."

He started the slow return to level ground, one careful step after the other, one firm hand securing his hold on Merlin, the other used for leverage as he moved. Merlin dangled across his shoulder, too weary to worry much about what would happen if Arthur lost his footing.

At long last they reached safe ground at the forest's edge. Arthur's legs were trembling with exhaustion as he placed Merlin on the ground under a fir tree, once more pulling him close so that they could share what little body warmth they had left between them.

There was a sound nearby, as if a horse nickering softly. 

"Did you hear that?" Arthur murmured after a moment. "Do you think it's your horse, or mine? It would make things so much easier."

"Let's wait until daylight," Merlin whispered. "It's so dark, and I'm so tired..."

Arthur chuckled wearily, squeezing Merlin's shoulders lightly. "Tell me about it."

They slept.

*****

Once the morning light awoke them, they faced off in the green and muted light under the heavy fir branches.

"So," Arthur said, looking Merlin square in the eye. "You have magic, too."

Merlin fought the nausea roiling in his guts. He felt clammy with sweat, and he had a terrible headache. It was the worst possible time to have this out with Arthur. 

"Yes, I was born with it. But I only ever use my magic to help you, Arthur," Merlin said. "Only for you, and for the good of Camelot."

"You've lied to me all this time," Arthur said. The expression on his weather-lashed face was inscrutable. "You've been pretending to be a clumsy idiot, while in reality—"

Merlin fought an urge to vomit. "What else could I do? Your father - and you - would have burnt me at the stake if you knew. I wanted to stay close to you. I had no choice."

"How can I trust you completely after this?"

Merlin clutched at his stomach. It was cramping up. "I saved you yesterday. I will always help and protect you, if you'll let me."

Arthur crawled closer, looking into Merlin's eyes. Suddenly, his voice was full of concern. "Merlin, what is it? Your eyes are turning black. Your face is— you hardly look human!"

Merlin convulsed. He screamed in agony. 

Arthur got up, grabbed Merlin by the arms, and pulled him out in the open. He held Merlin close, trying to still his violent movements. "Tell me what to do. Merlin! What is happening?"

Merlin was writhing on the ground, seizures ravaging his entire body. He felt his consciousness blurring, slipping away, and something else, something monstrous, emerging within him. He opened his mouth to talk, or to scream, and an inhuman roar emerged. 

Finally, he understood. He looked at his own writhing hands. The skin was cracking, stretching, splotched with bluish-black. He couldn't stop it.

"Arthur, I'm turning into Cetus. The magic I consumed was too strong, it's taking over."

"Fight it! Merlin, you have to fight it—"

"I can't!" Merlin felt as if his head was bursting open, the pain was so severe. He convulsed again, and Arthur barely managed to hold him. 

"You fought the beast and won, you can do it again. Fight!"

Merlin tried. He truly did. It was no use. His own magic was to him as a young sapling standing in the path of an avalanche. He was losing. And that meant—

"Arthur, take Excalibur. Kill me. Kill me, before it's too late! When this transformation is complete, I'll be Cetus, and I'll devour you."

"Never. Merlin, fight! Don't give up."

Merlin roared, his head snapping back, his vision going blurry. He was losing the last remnants of control of all that was him, all that was his magic. In consuming Cetus's too-immense power, he'd ensured his own demise.

"You have to stop me, or Camelot is doomed. Kill me, I beg you!"

Arthur got to his feet. There were tears in his eyes. "Camelot's not doomed if I give my life to the monster. That was my intention all along. Merlin, I can't kill you. I love you."

Merlin's whole heart and the part of his mind that was still his own, filled with sudden immense joy, strong enough to suppress the pain and horror for a moment. But most of all, he felt grief. It was too late for them. It was over. 

"If you love me, please use Excalibur. Please. Do you want to see me disappearing into this horrid shape to live an eternity as a monster?"

Arthur stood above him, his face pale and drawn, indecision carved into every tense line. He watched Merlin writhing on the ground, limbs increasingly contorted, skin cracking apart, mouth wide open to reveal emerging fangs. Merlin roared again. The monster was obviously winning. 

Setting his jaw and drawing a deep breath, Arthur made a decision. He raised Excalibur to deal a lethal blow. Tears rolled down his cheeks as he did so.

"Âgieldan êower eafoð âdôn me," Morgana said, her eyes fixed on Merlin as she stepped forward to stand next to Arthur. 

Arthur lowered the sword, too stunned to hold it aloft. He turned to his sister in utter disbelief. She looked like a warrior queen, dressed in silver chainmail, her long hair tied back in a braid, and with a sword at her side. 

Morgana kept her full attention on Merlin. Her eyes glowed like the brightest sun as she reached out to him, repeating her command in a loud and confident voice. "Âgieldan êower eafoð âdôn me!"

The tiny remaining part of Merlin felt a sudden surge of hope. It was as if he was locked far inside himself, helpless, being squeezed into nothingness, but he could still look out through Cetus's eyes. To Cetus, Morgana seemed like a creature of blazing light. The monster inside, the monster Merlin had become, tried to fight off her spell, but could not disobey it. 

Little by little, as he continued twisting on the ground, raging against Morgana's intrusion, Cetus's powers left Merlin. Dark magic poured out like black smoke, which was consumed by Morgana's light. The pain lessened. The monster lost control of him, and Merlin once more felt himself in charge of his own body, mind and magical powers. He rolled over, crawled onto his knees, and slowly managed to stand up.

He could see Arthur to the side, wide-eyed, sword tip resting on the ground, looking back and forth between his manservant and his half-sister, powerful sorcery blazing between the two of them.

Morgana continued to pull Cetus's powers into herself, chanting the vanquishing spell over and again. "Âgieldan êower eafoð âdôn me."

Merlin could still feel parts of the ancient, dark magic shuddering inside, an entirely alien entity, distinct from his own innate magic. Cetus was not in control anymore, its powers lessening moment by moment. Realization dawned on Merlin. The monster had been too strong for him. If he let Morgana take all its powers, it would certainly also overpower her. He couldn't let that happen.

He raised his right hand in a forbidding gesture."Belūc! _Stop!_ "

The flow of magic was severed as if cut with a knife. Morgana stumbled backwards. Her eyes lost their glow. 

"Merlin, no! I wasn't finished," she cried.

"We are both finished," Merlin said. "I can control what of Cetus remains within me. You will be able to control what you've consumed. This way, Cetus truly has been vanquished forever."

Morgana closed her eyes, swaying slightly on her feet. "I think you're right," she mumbled after a moment.

The three of them stood silently on the coarse grass just beyond the cliffs. They all looked as if they'd barely survived a hurricane. Merlin's jacket and tunic were in tatters. Only his red neckerchief had somehow survived intact. 

They could smell the ocean and hear the distant cries of gulls, soaring on the winds above the sea-cliffs and rocks. It was an overcast day, but there was no rain, and the air was refreshing. 

Only a day ago, Merlin had served Arthur and Morgana lunch back in Camelot. Everything had changed since then; who they were, and what they knew - about themselves, as well as about each other.

"Is that really the end of it?" Arthur shook his head in wonder. "Is Cetus gone for good?"

"Yes," Merlin affirmed.

"I think so," Morgana nodded. "I feel Cetus's darkness inside, but Merlin and I shared the power equally. I don't think my part will overpower me. I hope not. I may even control it, once I learn to use magic properly."

"What Cetus has left us with is tempting and dangerous," Merlin warned. "We will both be a little more fey because of it, and will always have to be on our guard. This victory did come at a cost." 

"Do I need to distrust you, then?" Arthur asked, worried and wary.

"No, never," Merlin said. "I and my magic are yours for good, to have and to hold and command, until death and beyond."

"Listen to the song of your true magical lovebird, Arthur," Morgana grinned, pushing loose wisps of hair out of her eyes.

Merlin and Arthur both opened their mouths to speak, but Morgana hadn't finished. "Do you still mean to uphold Camelot's ban on magic? In that case, Merlin and I have every reason to distrust _you_ , Arthur. And I have yet another reason to be wary, of course. You tried to drug me with a sleeping potion, you sneak."

Arthur looked at her. "Yes, but—"

"You did it for my own good? You wanted to protect me? Now, where have you recently heard the same sort of argument, hmm?" Morgana nodded pointedly in Merlin's direction. She shrugged. "No-one knows the taste of Gaius's sleeping potions better than me, Arthur. One sip, and I _knew._ I only pretended to drink the wine you so generously poured."

"You followed me?"

"I did, although I lost track of you for a while, and nearly arrived too late. I was rushing to get you off that rock when Merlin showed up and started using magic, more spectacular than thunderstorms and fireworks combined. I was too stunned to move or speak."

Merlin cleared his throat sheepishly. "Ehm, yes, that must have been— surprising." 

Morgana rolled her eyes and arched a perfect eyebrow at him, before turning her attention back to Arthur. "I stood at the forest edge and watched you, Merlin and Cetus battling it out against the sinking sun, a drama that I will never, ever forget. I was transfixed. Merlin's spell stuck in my mind. As soon as you two had crawled in under those branches for the night, I went to look after my horse. I'd left her still wearing saddle, bit and bridle, the poor thing. By then I was exhausted and slept where I found her. After all, it's been a _very_ trying few days."

Arthur couldn't help laughing. "The understatement of the century, right there. But here we are, against the odds, all three of us alive, and the monster is gone."

"Yet everything has changed," Morgana said. "So many secrets have been revealed, so many truths are out in the open, and our relationship will never be the same."

"True." Arthur shook his head in wonder. "You are my sister, and a seer and sorceress. Merlin is a sorcerer, and will hopefully soon be my consort. The both of you possess monster powers. It's unbelievable. And no, in answer to your question, I will certainly not uphold the ban on magic. You two have just saved my life and all of Camelot. I want to thank you, not persecute you."

"A new dawn for Camelot." Morgana's smile was warm and genuine.

"Consort?" Merlin asked Arthur. His cheeks had turned pink.

"If you'll have me."

"Of course I'll have you, you utter and complete dollophead! I love you."

"What did you call me? Wait— you really love me?"

"With all my heart. I never thought I'd get to say it out loud, though."

"Merlin..." Arthur pulled Merlin into his arms and let action speak where words would not suffice. He kissed Merlin, gently at first, but soon their kiss turned heated. Arthur cradled Merlin's dark head with one hand, while Merlin threw both arms around Arthur's neck. A soft moan escaped from between their joined lips.

"How sweet," Morgana muttered. "Although not unexpected. Never mind me, boys. I've dreamed of this anyway."

Arthur pulled back, blushing. "Morgana!"

Morgana grinned. "I've _literally_ dreamed of if, brother dear. I'm a seer, remember?"

"Oh. You mean you dream of—"

Morgana gestured dismissively. "I'm sure we'll be much more comfortable continuing - whatever you want to continue - back at the castle. Let's think of getting back to Camelot. I'm hungry, and tired, and I might just be ready to kill for a warm bath."

"Can't have that," Arthur exclaimed in mock horror. "You're right, of course. Let's go. Merlin, can you and your magic manage to call our horses back from wherever they've run off to?"

"Your wish is my command," Merlin smiled, his eyes going golden.

"With a magical sword, and with you two by my side, imagine what I can accomplish," Arthur mused aloud. "We can do so much for Camelot, for Albion!"

"You'll be a legendary king, Arthur."

"We'll all be legends."

Arthur laughed, took Merlin's hand, and smiled at his sister. "Maybe. But one thing at a time. First, let's get back home, so we can reassure everyone that the danger is over, and then we should have ourselves a proper meal. I'm starving!"

** THE END ** 

**Author's Note:**

> Cetus is a creature from Greek mythology, a sea-monster who ravaged the coast of North Africa and required Princess Andromeda as sacrifice. Perseus saved the unfortunate Andromeda, and killed the monster.
> 
> Many artworks depict the battle between Perseus and Cetus and the rescue of Andromeda. Cetus is usually shown as dragon-like or as a huge snake. I have mainly been inspired by the (NSFW) painting 'The Doom Fulfilled' by Edward Burne-Jones, and also (when it comes to Cetus's actual look) by various illustrations of Norse mythology's Jörmungandr, the sea-monster that encircles the world.


End file.
